It's not unprofitable. You clearly don't understand it yet.
They can mine any Scrypt coin and Viacoin for free as bonus.

Lots of mining pools do this. Like F2pool and litecoinpool.org
Both mine litecoin and Viacoin at the same time. They won't stop because they get the Viacoins as bonus. Hence the high hashrate. The hashrate doesn't lie. The hashrate of Viacoin up/down moves is similar to that from litecoin. When litecoin hashrate is high, so is that from Viacoin.